Tumor immune evasion is a fundamental hallmark of cancer progression and a major barrier to effective immunotherapy. RNA epitranscriptomic modifications have emerged as a critical layer of post-transcriptional regulation that links RNA fate control with tumor immune remodeling. These reversible modifications, including m6A, m5C, ac4C, m¹A, m7G, pseudouridine, m6Am, Nm, and A-to-I RNA editing, are dynamically regulated by writers, erasers, and readers. By modulating RNA stability, splicing, nuclear export, translation efficiency, degradation, and innate immune recognition, RNA modifications reshape multiple immune-related processes in cancer. Mechanistically, they regulate tumor immune visibility by influencing antigen processing, MHC-I expression, interferon signaling, and dendritic cell-mediated cross-presentation. They also control immune checkpoint expression, particularly the PD-1/PD-L1 axis, inflammatory signaling pathways, immune-cell recruitment and exhaustion, and metabolic immunosuppression within the tumor immune microenvironment. Importantly, the functions of RNA modification regulators are highly context dependent. The same regulator may either promote immune escape or enhance antitumor immunity depending on cancer type, cellular source, target transcript, reader protein, and microenvironmental state. From a clinical perspective, RNA modification-based molecular subtypes, prognostic signatures, and risk-score models show potential for predicting patient prognosis, immune infiltration, and response to immune checkpoint blockade. In parallel, targeting RNA modification regulators, alone or in combination with immunotherapy, radiotherapy, chemotherapy, or targeted therapy, represents an emerging therapeutic strategy. However, clinical translation remains limited by insufficient specificity, tumor heterogeneity, complex crosstalk among RNA modifications, potential toxicity, and delivery barriers. Future studies integrating RNA modification mapping with single-cell, spatial, and multi-omics technologies will be essential to define cell-type-specific regulatory networks and develop precise RNA epitranscriptomic biomarkers and therapies for cancer immunotherapy.
